#importing modules
import math
from __future__ import division
#Variable declaration
r = 0.052; #radius of orbit(nm)
B = 1; #magnetic field(Wb/m**2)
e = 1.6*10**-19; #charge of electron(c)
m = 9.1*10**-31; #mass of electron(kg)
#Calculation
r = r*10**-9; #radius of orbit(m)
delta_mew = (e**2)*(r**2)*B/(4*m); #change in magnetic moment(Am**2)
#Result
print "change in magnetic moment is",round(delta_mew/1e-29,3),"*10**-29 Am**2"
print "answer given in the book is wrong"